21620040 has 64 divisors (see below), whose sum is σ = 69854400. Its totient is φ = 5321472.

The previous prime is 21620021. The next prime is 21620059. The reversal of 21620040 is 4002612.

It is an interprime number because it is at equal distance from previous prime (21620021) and next prime (21620059).

It is a super-2 number, since 2×21620040² = 934852259203200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5370 + ... + 8489.

It is an arithmetic number, because the mean of its divisors is an integer number (1091475).

Almost surely, 2^21620040 is an apocalyptic number.

21620040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21620040 is an abundant number, since it is smaller than the sum of its proper divisors (48234360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21620040 is a wasteful number, since it uses less digits than its factorization.

21620040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13886 (or 13882 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21620040 is about 4649.7354763470. The cubic root of 21620040 is about 278.5814306543.

Adding to 21620040 its reverse (4002612), we get a palindrome (25622652).

The spelling of 21620040 in words is "twenty-one million, six hundred twenty thousand, forty".